Copper-lead-smelting process



W. McA. lOHNSON COPPER LEAD SMELTlNG PROCESS. APPLlCATl-QN, FILED OCT. 24, 1914.

1 ,333, 720 Patented Mar. 16, 1920.

Basic Ore a 0 High Felq 0 Fusmq umb/#00 hi I Qofarl; Kiln filiel Collector Slaq Matte Lead lstElectric Settling Hearth Coke Slag

Matte Lead 2nd. Electric Settling Hearth INVENTQR BY EWQM ATTORNEY wooLsEY MoALPINE JOHNSON, or iranr'ronn, CONNECTICUT.

ooPrEn-LEAD-sMntrmG rnocnss.

Specification of Letters Patent. Patentd Mar. 16, 1920.

Applicaton filed October 24, 1914. Serial No. 868,488.

To all whom it may concern:

Be it. known thatI, WVooLsnY McA. J OHN- s' x, a citizen of the United States, and residing at Hartford, in' the countyof Hartford and State of Connecticut, have invented a new and Improved Copper-Lead-smelting Process, of which the following specification is a full disclosure.

This invention deals with a combination smelting system suitable for lead-copper ores and .devised to operate under conditions of maximum eiliciency by selectively utilizing the thermal energy of fuel and of electricity.

As a general proposition, coke is expensive in mining centers, whereas soft-coal is comparatively cheap; yet the coke is used for the reason that it enables smelting to be done in a shaft furnace, which is a good metallurgical instrument. Electricity, however, can be utilized in such a way as to be more efficient for temperatures above 1100 C.', for it is a powerful heating and metallurgical agent enabling one to, put heat just where desired when its conditions of use are fully understood and when it is rightly applied.

My new processJcomprehends the heating (by the flame of combustion of softcoal') two kinds of oxidized ores in two separate rotary furnaces (c. 9., hot calcined or naturally oxidized ore), with such additions of.

such ingredients as may benecessary and suitable.

My ne-w process will be understood by ref-- erence to the accompanying diagrammatic drawingiand in connection with the following disclosure.

The first of these mixtures (A) is made or selected so as to contain a large percentage of metallic oxids, such as CaOFe O and it is relatively basic and therefore has a high fusing point.

' ent, the fusing point'of this mixture w' 1 be about 14:00 O. Isinter such material in a rotary furnace, similar to a cement kiln. and fired either with oil, coaldust or gas. The other mixture (B) is made principally of silicious' material. and likewise has a high fusing point. As in case of the mixture (A), the finishing temperature isbelo'w the fusing temperature by a safe margin. The operation of mixture (B) is likewise carried on in a rotary furnace 4 If these two were heated together, a semifused mass that would not feed would be made. Accordingly, mixture is ted Provided 20% CaO is )res with mixture (B) into an electric furnace preferably of the buried-arc type in which the electrode is submerged in theslag and the charge. These mixtures and (B) are fed into the electric furnace in such proportions that a slag will be made analyz-- ing about: I 1

s 0. sea,

(laO :'=20% FeO 30% ZnO 10% In this operation, lead bullion and copper settler, some fine carbonaceous material, such as coke from a gas producer or fire box;

added to reduce the contained ZnO from about 10% to-about 1%; and to increase the reductivity of this auxiliary smelting zone so that it may also reduce any dissolved 0110 or PhD. No special attempt need be made to reduce the zinc vapor to spelter, although from 15% to 35% of the zinc vapor will be condensed to spelter under the conditions prevailing. Preferably, the yapor ismainly condensed to impure blue-powder. This can be sold asa raw material or can be electrically smelted on the spot to make spelter.

In case much lead is present ins(A) or in (B) and-in case anextremely high-temperature isused, it will be necessary to use abag 1 house or Cottrell apparatus to prec pitate any of the lead pass ng away as fume. In

certain instances, itwil'l be advisable to make a third mixture C; using a separate third pro-heater, which is high in lead, (or for example lead-concentration) and which is subjected to only such a temperature (000 C.) that no commercial loss of lead can ensue. This does away with expensive dust and fume collecting devices.

In certain cases, as where no lead is present in ore, percentages of copper oxid and of copper sulfid are so proportioned that this reaction takes place and a copper bullion isthus made directly iron! ore. In that event, the'slag in the forehearth is given a sprinkling of low-grade copper pyrites charged with coil to clean the slag of any copper pellets contained in 1t by making. a low grade matte in saidforehearth; a slag containing an excess of iron sulfid is much cleaner than a slag without appreciable sulfid present.

The electricity is used only in small amounts. Assuming thesmelting is conducted at 1300 (3., and that the pie-heat ng is done at 1200 (l, the net electrothermal requirements per metric ton will be low since considerable heat is evolved, in fact enough to carry on all the smelting work, and the electrical heat is only supplied to increase the smelting rate by increasing the working temperature ofthe smelting zone abovethe critical temperatures at which .the reactions start. The electricity thus plays a role in my process similar to that played by small percentage of coke in pyritie smelting, only in a much more effectual manner.

In the matter of the 'compositim of the slag, my process hasan advantage over a lead-blast furnace because in the latter the slag must be held within close limits. In my process the slag's can range widely in com- Ag 0. 50 oz. per ton. Au None.

This result was attained by a reductivity in the smelting zone su 'ciently intense to reduce the zinc compounds, '(2) by having a hot fluid slag through which no blast pene trates, and (3) by'the aid of the throbbing and pulsating action of the alternating current.

If a small amount of coke breeze be added to the smelting furnace and if the electrode etsam passes through roof by means of a watercooled stuffing box, the accidental oxidation of the electrodes will be slight and the [electrode consumptionper ton of ore will not amount to 'ov'er' lbs. per ton.

Having thus revealed this invention, I claim as new and desire to secure the following combinations of elements, or equivalents thereof, by Letters Patent of the United States 1. A smelting process which comprehends bringing an acid and a basic ore mixture separately to high temperatures by heat derivedfrom the combustion offuel; and then associating said mixtures within a closed} container and therein subjecting them to smelting conditions by means of internally developed heat.

2. A smelting process which comprehends bringing an acid and a basic bre mixture separately to high temperatures by heat derived from the combustion of fuel; and then associating'said mixtures and subjecting them to smelting conditions by means of heat derived from electrical energy within a closed furnace. l

3. A process of smelting ores bearing large proportions of copper and lead which comprehends separately heating to a tempera-v ture closely approximating the fiuxing point an acid and a basic mixture containing said metals by combustion of fuel; and then simultaneously subjecting said pro-heated mixtures to smelting conditions within an electric furnace.

. p 4. A smelting process which comprclhends heating to a temperature not less than 1200 degrees C. of oxidized ores 111 two separate continuous furnaces by means of heat (le introducing said ores into an electric furnace and thereupon raising the temperature thereof to a sufficient degree to effect smelting.

' In witness whereof, I hereunto subscribe my name, as attested by the two subscribing witnesses.

wootssr MeALPINE JOHNSON.

Witnesses B. COOKE, L. Lnvrr.

"rived from the combustion of fuel; and then 

